Since February last year suspected militants have killed several secular or atheist writers and members of religious minority groups.

BBC Bengali Service editor Sabir Mustafa said staff at Roopbaan, which had not been condemned by the government and received some support from foreign embassies, had been careful to protect their identities but had not believed their lives were at risk.

Suspected extremists in Bangladesh are gaining a sense of security that they can carry out killings with impunity, he says. Meanwhile Bangladesh’s best known blogger said he had received a death threat on Sunday.

Imran Sarker, who led major protests by secular activists in 2013 against Islamist leaders, said he had received a phone call warning that he would be killed “very soon”.

Earlier this month, a Bangladeshi law student who had expressed secular views online died when he was hacked with machetes and then shot in Dhaka.

Last year, four prominent secular bloggers were also killed with machetes. The four bloggers had all appeared on a list of 84 “atheist bloggers” drawn up by Islamic groups in 2013 and widely circulated.

There have also been attacks on members of religious minorities including Shia, Sufi and Ahmadi Muslims, Christians and Hindus.

Muslim-majority Bangladesh is officially secular but critics say the government has failed to properly address the attacks.